Genetics Lab midterm
genes that are likely to be inherited together because they are physically close to one another on the same chromosome; the physical relationship between genes
Linked Genes
The Dihybrid Recessive Backcross is the primary cross that we will use throughout this laboratory to examine linkage
True
A mating between two organisms with different variations at one genetic locus of interest
monohybrid cross
chi-squared formula
sum of (observed-expected)^2/expected
__________ is a "signature" ratio for the Recessive Lethal Mode of Inheritance
2:1
Diploid organisms have __________ possible genotypes at each locus.
3
Fruit flies have _____ pairs of chromosomes.
4
In a dihybrid cross, if two heterozygotes (for both genes) are crossed once, what will be the expected phenotypic ratios? (In the following order: dominant for both traits; dominant for the first trait recessive for the second; recessive for the first trait and dominant for the second; recessive for both traits)
9:3:3:1
In fruit flies, Wild wing shape is dominant over Crumbled wing shape. Wild eye shape is dominant over Eyeless eye shape. using the Electronic Fly Colony you select the following Parental cross. Wild, Wild Male x Crumpled, Eyeless Female. Select the 2 genotypes that would correspond to these phenotypes
AABB male aabb female
Assume that allele A is dominant to a, and B is dominant to b. Match each of the following crosses with the expected phenotypic ratio AaBb x aabb: __________ Aabb x AaBb: __________ AaBb x AaBb: __________
AaBb x aabb: 1:1:1:1 Aabb x AaBb: 3:1:3:1 AaBb x AaBb: 9:3:3:1
Expression of the heterozygote phenotype results in BOTH phenotypes being expressed
Codominance
A mating between two organisms with different variations at two genetic loci of interest
Dihybrid cross
The Fly Colony module used this week has a major difference from the previous weeks. Once you select a F1 offspring to use an F2 parent, the program automatically selects the other parent to be a Dihybrid Double Recessive genotype. This choice assures that the expected mendelian assortment ratio will always be 9:3:3:1
False
the alleles of two (or more) different genes get sorted into gametes completely independently of one another
Law of independent assortment
Expression of the heterozygote phenotype forms an intermediate that is distinct from parents
Incomplete Dominance
When new combinations of the genes in the progeny are formed due to crossing over between genes present on homologous chromosomes
Incomplete Linkage
If the gene for pea color is inherited separately from the gene for pea shape, and thus the allele occurrence for one trait does not affect the other, then this demonstrates the law of __________.
Independent Assortment
Linkage is considered to be a violation of Mendel's Principle of __________.
Independent Assortment
Alleles that cause the death of the organism that carries them and are usually a result of mutations in genes that are essential for growth or development
Lethal Alleles
You cross 1000 fruit flies with the genotype Aa and obtain the following results: AA: 208 Aa: 511 What mode of inheritance best fits these results?
Lethal Alleles
Allele pairs separate and segregate during gamete formation (meiosis) and randomly unite at fertilization
Law of Segregation
Diploid organisms have a limited number of potential crosses. These crosses are referred to as: __________
Mendel's Big Six
Phenotypic expression of an allele that is dependent on the gender of the individual and is directly tied to the sex chromosome
Sex Linkage
Using the __________ Rule, you can multiply the probabilities of two segregation ratios to get the assortment ratio
Product
When performing a __________ and the F2 generations yield significantly different results, it is likely that the trait is sex linked.
Reciprocal cross
the rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA from different organisms.
Recombination
The basic dominant/recessive relationship is also commonly referred to as __________
Simple mendelian
All loci located on Chromosome Pair 1 of fruit flies would exhibit sex-linked mode of inheritance
True
You have performed a dihybrid recessive backcross, and you find that you do NOT get a 1:1:1:1 ratio. This means:
The genes are linked- they are on the same chromosome
In 3-point mapping what are the double cross overs?
The least amount of offspring produced
After setting up a dihybrid backcross, if you fail to reject your null hypothesis, what can you infer about the linkage of loci in question?
The loci are assorting independently
In 3-point mapping what are the parentals?
The most amount of offspring produced
The phenotype of the flies most commonly captured in "the wild" is referred to as the __________.
Wild type
presence of different sex chromosomes
lygaues mode
The alternative forms of a gene are known as __________
alleles
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
alleles
A person with the phenotype of AB for blood type has the genotype AB. What is the relationship between the A allele and B allele?
co-dominant
What type of dominance is demonstrated by the progeny expressing the phenotype of both parents?
codominance
When two loci are so close together that alleles of these loci are never separated by crossing over
complete linkage
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.
cross over
Phenotype 1 is dominant to phenotype 2 IF the heterozygote has phenotype 1
dominant
If chi-squared value is less than the table value
fail-to-reject
refers to a particular gene having two different alleles of homologous chromosomes
heterozygous
a gene inherited in two species from a common ancestor
homolog
Refers to a particular gene that has identical alleles on homologous chromosomes
homozygous
For the Mendelian option, the Fly Clone program is designed so that the F1 progeny are all heterozygotes. This result stimulates exactly what happens if new ere crossing real flies and occurs because one Parent is __________ dominant while the other is selected to be __________ recessive.
homozygous/ homozygous
The reduction in the probability of occurrence of crossover at one location on a chromosome due to crossover occurring in another location
interference
The position of a gene or mutation on a chromosome.
loci
What do you call the physical expression of a gene?
phenotype
Phenotype 2 is recessive to phenotype 1 IF the heterozygote has phenotype 1
recessive
The frequency with which a single chromosomal crossover will take place between two genes during meiosis
recombination frequency
If the chi-squared value is more than the table value
reject
When each parent has on mutant allele and one wild type allele, the configuration is referred to as __________
trans or repulsed